/* ========================================================================
 * JCommon : a free general purpose class library for the Java(tm) platform
 * ========================================================================
 *
 * (C) Copyright 2000-2004, by Object Refinery Limited and Contributors.
 * 
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * 
 * -------------------------
 * DefaultConfiguration.java
 * -------------------------
 * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: DefaultConfiguration.java,v 1.2 2004/10/06 21:45:13 taqua Exp $
 *
 * Changes
 * -------
 * 04.06.2003 : Initial version (TM);
 *
 */

package org.jfree.util;

import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Properties;
import java.util.TreeSet;

/**
 * Default configuration.
 * 
 * @author Thomas Morgner.
 * 
 */
public class DefaultConfiguration extends Properties implements Configuration {

    /**
     * Creates an empty property list with no default values.
     */
    public DefaultConfiguration() {
        super();
    }

    /**
     * Returns the configuration property with the specified key.
     *
     * @param key  the property key.
     *
     * @return the property value.
     */
    public String getConfigProperty(final String key) {
        return getProperty(key);
    }

    /**
     * Returns the configuration property with the specified key (or the specified default value
     * if there is no such property).
     * <p>
     * If the property is not defined in this configuration, the code will lookup the property in
     * the parent configuration.
     *
     * @param key  the property key.
     * @param defaultValue  the default value.
     *
     * @return the property value.
     */
    public String getConfigProperty(final String key, final String defaultValue) {
        return getProperty(key, defaultValue);
    }

    /**
     * Searches all property keys that start with a given prefix.
     *
     * @param prefix the prefix that all selected property keys should share
     * @return the properties as iterator.
     */
    public Iterator findPropertyKeys(final String prefix) {
        final TreeSet collector = new TreeSet();
        final Enumeration enum1 = keys();
        while (enum1.hasMoreElements()) {
            final String key = (String) enum1.nextElement();
            if (key.startsWith(prefix)) {
                if (collector.contains(key) == false) {
                    collector.add(key);
                }
            }
        }
        return Collections.unmodifiableSet(collector).iterator();
    }


}
